That’s true, but it was intended to impoverish whites more. You can’t revenge on somebody who could leave.
Just WHO were "necklaced" and why; do you know?
It was mostly done to those who belong to the Zulu tribe. WHY? Because they didn't belong to nor vote for the ANC and were the tribe that brought the Xhosas ( *spit* "Saint Nelson's" tribe ) into what is now the RSA, as SLAVES.
It is also far easier ( though still NOT "easy" ! ) for a RSA black to leave than a white and yes, there always were educated, wealthy blacks in South Africa.